homebrew-core/Formula/emscripten.rb

require "language/node"

class Emscripten < Formula
  desc "LLVM bytecode to JavaScript compiler"
  homepage "https://emscripten.org/"
  url "https://github.com/emscripten-core/emscripten/archive/2.0.14.tar.gz"
  sha256 "8faf0ccb5a72cf7e6516b9f9461d763783c7b8ef877d403f957b9c9b36f4c075"
  # Emscripten is available under 2 licenses, the MIT license and the
  # University of Illinois/NCSA Open Source License.
  license all_of: [
    "MIT",
    "Apache-2.0", # binaryen
    "Apache-2.0" => { with: "LLVM-exception" }, # llvm
  ]
  head "https://github.com/emscripten-core/emscripten.git"

  livecheck do
    url :stable
    regex(/^v?(\d+(?:\.\d+)+)$/i)
  end

  bottle do
    sha256 cellar: :any, arm64_big_sur: "92359f957c80f52fd8cb477a5ce0f4b68e5d5d05ae6aa5ee95f9605460135dfb"
    sha256 cellar: :any, big_sur:       "92ee5db54d289ca44c95c834cfb5102872bec8389826f143f435f10be2661ae2"
    sha256 cellar: :any, catalina:      "d0c15dccbbf9c5a4d02a399cd5a13b11e30b13f8c8f9b2465b39abbbdb1f6155"
    sha256 cellar: :any, mojave:        "285f68f73a7ce563864184dc6812a0b37dadafc2b93235b86e1015899a6c82d6"
  end

  depends_on "cmake" => :build
  depends_on "node"
  depends_on "python@3.9"
  depends_on "yuicompressor"

  # Use emscripten's recommended binaryen revision to avoid build failures.
  # See llvm resource below for instructions on how to update this.
  resource "binaryen" do
    url "https://github.com/WebAssembly/binaryen.git",
        revision: "c12cc3f50c0ef798b218739fc3de06237ea2c5d5"
  end

  # emscripten needs argument '-fignore-exceptions', which is only available in llvm >= 12
  # To find the correct llvm revision, find a corresponding commit at:
  # https://github.com/emscripten-core/emsdk/blob/master/emscripten-releases-tags.txt
  # Then take this commit and go to:
  # https://chromium.googlesource.com/emscripten-releases/+/<commit>/DEPS
  # Then use the listed llvm_project_revision for the resource below.
  resource "llvm" do
    url "https://github.com/llvm/llvm-project.git",
        revision: "5f3c99085d4c2ebf57fd0586b013b02e32a8e20b"
  end

  def install
    ENV.cxx11

    # All files from the repository are required as emscripten is a collection
    # of scripts which need to be installed in the same layout as in the Git
    # repository.
    libexec.install Dir["*"]

    # emscripten needs an llvm build with the following executables:
    # https://github.com/emscripten-core/emscripten/blob/#{version}/docs/packaging.md#dependencies
    resource("llvm").stage do
      projects = %w[
        clang
        lld
      ]

      targets = %w[
        host
        WebAssembly
      ]

      llvmpath = Pathname.pwd/"llvm"

      # Apple's libstdc++ is too old to build LLVM
      ENV.libcxx if ENV.compiler == :clang

      # compiler-rt has some iOS simulator features that require i386 symbols
      # I'm assuming the rest of clang needs support too for 32-bit compilation
      # to work correctly, but if not, perhaps universal binaries could be
      # limited to compiler-rt. llvm makes this somewhat easier because compiler-rt
      # can almost be treated as an entirely different build from llvm.
      ENV.permit_arch_flags

      args = std_cmake_args.reject { |s| s["CMAKE_INSTALL_PREFIX"] } + %W[
        -DCMAKE_INSTALL_PREFIX=#{libexec}/llvm
        -DLLVM_ENABLE_PROJECTS=#{projects.join(";")}
        -DLLVM_TARGETS_TO_BUILD=#{targets.join(";")}
        -DLLVM_LINK_LLVM_DYLIB=ON
        -DLLVM_BUILD_LLVM_DYLIB=ON
        -DLLVM_INCLUDE_EXAMPLES=OFF
        -DLLVM_INCLUDE_TESTS=OFF
        -DLLVM_INSTALL_UTILS=OFF
      ]

      sdk = MacOS.sdk_path_if_needed
      args << "-DDEFAULT_SYSROOT=#{sdk}" if sdk

      if MacOS.version == :mojave && MacOS::CLT.installed?
        # Mojave CLT linker via software update is older than Xcode.
        # Use it to retain compatibility.
        args << "-DCMAKE_LINKER=/Library/Developer/CommandLineTools/usr/bin/ld"
      end

      mkdir llvmpath/"build" do
        # We can use `make` and `make install` here, but prefer these commands
        # for consistency with the llvm formula.
        system "cmake", "-G", "Unix Makefiles", "..", *args
        system "cmake", "--build", "."
        system "cmake", "--build", ".", "--target", "install"
      end
    end

    resource("binaryen").stage do
      args = std_cmake_args.reject { |s| s["CMAKE_INSTALL_PREFIX"] } + %W[
        -DCMAKE_INSTALL_PREFIX=#{libexec}/binaryen
      ]

      system "cmake", ".", *args
      system "make", "install"
    end

    cd libexec do
      system "npm", "install", *Language::Node.local_npm_install_args
      rm_f "node_modules/ws/builderror.log" # Avoid references to Homebrew shims
    end

    %w[em++ em-config emar emcc emcmake emconfigure emlink.py emmake
       emranlib emrun emscons].each do |emscript|
      (bin/emscript).write_env_script libexec/emscript, PYTHON: Formula["python@3.9"].opt_bin/"python3"
    end
  end

  def post_install
    system bin/"emcc"
    inreplace "#{libexec}/.emscripten" do |s|
      s.gsub!(/^(LLVM_ROOT.*)/, "#\\1\nLLVM_ROOT = \"#{opt_libexec}/llvm/bin\"\\2")
      s.gsub!(/^(BINARYEN_ROOT.*)/, "#\\1\nBINARYEN_ROOT = \"#{opt_libexec}/binaryen\"\\2")
    end
  end

  test do
    # Fixes "Unsupported architecture" Xcode prepocessor error
    ENV.delete "CPATH"

    (testpath/"test.c").write <<~EOS
      #include <stdio.h>
      int main()
      {
        printf("Hello World!");
        return 0;
      }
    EOS

    system bin/"emcc", "test.c", "-o", "test.js", "-s", "NO_EXIT_RUNTIME=0"
    assert_equal "Hello World!", shell_output("node test.js").chomp
  end
end